peräsimestä

Peräsin refers to the rudder of a boat or ship. It is a control surface used for steering, typically attached to the stern or aft of the vessel. The primary function of the peräsin is to deflect water flow, creating a force that turns the vessel's bow in the desired direction.

The peräsin is usually a flat, hydrodynamically shaped piece of material, such as wood or metal. It pivots on a vertical or near-vertical axis. When the helm is turned, the peräsin moves from its central position, which is aligned with the vessel's direction of travel. This deflection of water causes a sideways force that rotates the vessel.

The size and shape of the peräsin are important design considerations, influencing the vessel's maneuverability and responsiveness. Larger vessels often have larger rudders, and their effectiveness is enhanced by the flow of water generated by the propeller. In some cases, multiple rudders may be used for increased control, especially on larger or more complex vessels. The peräsin is a fundamental component of most watercraft, enabling safe and effective navigation.